The Telerik UI for WPFs' API gives you the ability to configure the RadComboBox to support virtualization, which reduces the memory footprint of the application and speeds up the loading time thus enhancing additionally the UI performance. The purpose of this tutorial is to show you how to create a virtualized RadComboBox.

The standard layout system creates item containers and computes layout for each item associated with a list control. The word "virtualize" refers to a technique by which a subset of user interface (UI) elements are generated from a larger number of data items based on which items are visible on-screen. Generating many UI elements when only a few elements might be on the screen can adversely affect the performance of your application.

In some scenarios it is required to load thousands of items in a RadComboBox. By default the control creates RadComboBoxItem containers for each data item, so it might take some time to open the drop-down. To resolve the problem you just have to change the RadComboBox's ItemsPanel with VirtualizingStackPanel: